Even the largest shark ever to swim in the Earth's oceans was concerned about the safety of its young, according to researchers at the University of Florida.

Researchers have discovered a 10-million-year-old nursery believed to have belonged to the extinct megalodon shark.

The nursery, which contained more than 400 fossil shark teeth, was discovered in Panama in what used to be the shallow waters of the Gatun Formation that connected the Pacific and Caribbean seas.

Most of the teeth are believed to have belonged to juveniles that would've been between two and 10 metres in length, researchers said.

"Shark nursery areas are very poorly known, both for living and fossil species," said paleontology professor Michael Gottfried. "If the teeth from Panama ... do indeed come from a nursery area for giant megalodon shark, they have the potential to provide a lot of interesting information on the paleobiology of this enormous but still very enigmatic, fossil species."

The fossil evidence in the nursery shows the sharks likely used nurseries to protect their young for millions of years, said study author Catalina Pimiento.

Some scientists had believed megalodon sharks didn't keep nurseries to protect their young because they were the biggest shark that ever lived.